Dual control and lockout means for telephone stations



Jan. 11, 1949 G G. BRADLEY ET Al.

DUAL CONTROL AND LOCKOUT MEANS FOR TELEPHONE STATIONS Filed June 26, 1946 INVENTORS -,N. RMN

BY )f/W I ATTORNEY Patented Jan. 11, 1949 DUAL CONTROL AND LOCKOUT MEANS FOR TELEPHONE STATIONS George G. Bradley, Great Neck, and Harry F. y Mohr, Lynbrook, N. Y., assignors to Radio Corporation of America, a corporation of Delaware Application June 26, 1946, Serial No. 679,344

8 Claims.

c l, y This invention relates to remote control an lock-out circuits and has particular utility in connection with radio-telephone equipment.

In conventional radio telephone installations it is customary to mount the greater part of the equipment on a suitable enclosed rack remotely located with respect to the telephone hand-sets. These hand-sets are then associated with control units which may be placed advantageously at different points. For an installation on shipboard the radio operators cabin, and the wheel-house might be the two chosen locations for the control units.

It is among the objects of our invention:

(1) to provide a convenient circuit arrangement for radio-telephone equipment wherein it is required to obtain control from either one of two stations and to lock out the other station.

(2) To provide a switching arrangement which allows either of two control units to remotely operate a radio-telephone installation in order to place or to receive calls.

(3) to provide relay means in association with two control units whereby a transmitter-receiver unit may be placed in operation lfor a telephone conversation and may be rendered immune to inuence by the control unit which is Aidle.

The achievement of these objects makes its impossible for a conversation to be interrupted, listened to, or in any way interfered with by manipulating the switches or telephone hook at the unused control unit.

Our invention will now be described in more detail, reference being made to the accompanying drawing, the sole gure ofwhich shows diagrammatically a preferred embodiment, including switches and circuit arrangements suitable for carrying out the invention.

The control units A and B in their preferred embodiment are especially adapted for convenient use in a two-way radio telephone system of the marine type. These units include not only the switching arrangements shown within the broken line rectangles but also such other apparatus as may be needed for initiating and carrying on a f radio-telephone conversation and for receiving calls, as by ringing a bell. In a co-pending application of George G. Bradley, one of the joint applicants of the instant case, the novel features of such a telephone system are explained inmore detail. That application is identied as Serial No. 682,265 filed July 26, 1946, now abandoned.

The transmitter-receiver unit includes a motor generator 36 having a starter coil 40. Also ineluded in thel transmitter receiver-unit is the usual complement of transmitter apparatus 4| and one or more radio receivers 3l. The connections to the different transmitter and receiving units other than for4 switching purposes are not shown.

Two relays 34 and 35 are used for purposes of establishing and maintaining control from either one oi the control units A and B. Direct current power is supplied at terminals 38 and 39.

Switches I6 and 26 in the respective control units A and B are power switches either one of which can be used to turn the equipment on or oli. Switch I5 operates a movable contact I8 between stationary contacts Il and I9. Likewise, switch 26 operates a movable contact 28 between stationary contacts 2l and 29. Between the two control units conductors extend between contacts i9 and 23, also between contacts l'l and 21. Operation oi either one of the switches I6 and 25 therefore feeds positive potential to conductor 3 which is connected to the receivers 31 and also to relay contacts 2, 8 and l5. Still another connection is made from conductor 3 to one of the contacts 23 in a push-button switch 22.

When the equipment is rst turned on by means of either of the power switches I6 and 26 Y all of the control circuits are connected to the control uni-t B, since relay 34 is normally unenergized. Control may beswitched to control unit A by momentarily closing contacts 23 by means of the push-button 22. This energizes the relay 311 the circuit for which may be traced as follows: from conductor 3 through contacts 23, I3 and l2 of unenergized relay 35 and thence through the winding of relay 34 to the negative terminal 39 of the source.

Relay 35, when operated by push-button 22, is locked up through a circuit which may be traced from conductor 3 through contacts 2 and I, thence through normally closed contacts 33 of the push-button switch 32 in control unit B, thence through the winding of relay 34 and to the negative terminal 39 of the source.

When control unit -A has control, lifting ofthe hand-set oil of hook 2B closes a circuit between the hook 20 and contact 2l for the purpose of energizing relay 35. This circuit may be traced from live conductor 3 through relay contacts 8 and l, through contacts 2| and 23 (the hook), relay contacts ll and 5, and thence through the winding of relay 35 and to the negative terminal 39'. The closure of this circuit not only energizes relay 35, but also the starter coil All which is connected in shunt therewith. Coil di) serves to start the motor` generator which supplies direct current 3 of proper potentials to the circuits of the transmitter 4|.

Operation of relay 35 accomplishes two things: Firstly, the closing of contacts lli and l5 introduces a by-pass circuit around the manually operable power supply switches I6 and 25. Secondly, a circuit isestablished by closure of contacts Il and I2 in shunt with contacts 33 of the pushbutton switch 32, thereby disabling this switch. Hence, as long as the hand-set is off the hook at control unit A it is impossible to interrupt a conversation therefrom by operating either` of the switches 26 or 32. Furthermore, locking circuits for both relays 34 and 35 are rendered independent of the toggle and push-button switches at the two control units and can be opened only by returning the hand-set to its hook 26.

As soon as the conversation from control unit A has been completed and the hand-set replaced on hook 20, relay 35 becomes de-energized. Toggle switch .i6 may then. be thrown for the purpose of.. shuttingl downthe equipment, that is by opening the power supply circuit. Automatically, of course, relay 34 would be de-energized. The. power can now be turned on again at either of the control units by operation of one of the switchesl or,26.

Assume, for example, that control unit B is the one next to take control,V The switch lever 2.5 is

thrown andfeeds power to conductor 3 as before. 1

The lifting. of the handfset off the hook 39 operates relay 35' throughY a circuit which may be traced as follows-from live conductor 3 through contacts 8 and v5l (relay 3.4' remaining unenergized), through contacts 3B and Si, through contacts 6 and 5 tothe winding of relay 3,5 and from there to `the negative terminal 39.

Now, while relay 35 is energized and relay 34 is unenergized, the push button switchl 22 is disabled, relay contacts |2- and I3, and cannot be used to transfer control to control unit A, nor to interrupt a conversation carried on from control unit B. But as soon as the hand-set is returned to hook 3B, the locking circuit for relay 35 is opened.

The .operator a'tstation B now throws his switch 2S, opening, the` power supply circuit to conductor 3, if it is desired to shut down the equipment.

Withboth hand-sets hanging on their hooks it is possible for'either -control unit to be used to initiate or` to answer a call. Thisis true even if relay S4 should atY the time be locked up for the useoi' control unit` A. For then the push button 32v can be depressed for unlocking relay 3Il, whereat the control is restored to control unit B.

twill thus beseen from the above description that oui-'invention provides facilities for carrying out the stated objects. Furthermore, it will be understood ,that in the operation of relay 34 it is contemplated that-various circuits not shown in the drawing, but which may be essential to the operation of the radio telephone equipment, may be switched from control unit B. to-control unit A simply by the use of additionalcontacts 42 on the relay 34. The front and `back contacts associated with contacts 42'will, therefore, be seen to be useful for this transfer function.

Our invention may, of course, be modied in various respects without departing from its spirit and scope.

We claim;

l. Switching equipment for aradio-telephone installation of the type which provides that a call may be .initiated or respondedA to at either of two operating stations A and B, the main asthencc because of an open circuit condition at sembly of components of said installation being situated at a location remote from each of said stations, said equipment comprising a rst relay, at said location, energizable under control of a push-button switch located at station A and deenergizable under control of another push-button switch located atY station, B, said iirst relay con stituting means for transferring control from station B to station A, a hand-set hook switch at each station, and a second relay, at said location, energizable in response to the closure of the hook switch at the station from which control is efiective, said second relay having contacts through which circuits are established for protecting the used station against interference by the unused station.

2. Switching equipment for a radio-telephone installation of the type which includes a telephone hand-set at each of two stations and circuits connectable from each of said hand-sets to a centrally located unit which includes radio transmitting and receiving apparatus, said switching equipment comprising a power supply switch, a push-button switch and a telephone hook switch at eachsaid station, a iirst relay energizable after throwing either one of said power supply switches by manipulation of a particular one of said push-button switches, and de-energizable by manipulation of the other of said push-button switches, said relay constituting means for transferring; control of said centrally located unit fromv one to the other of said stations, and a second relay energizable in response to the closing of either of said telephone hook switches when lifting its handset therefrom, said second relay constituting means for maintaining exclusive control of said' centrally located unit from the station at which the hand-set is rst lifted from its hook.

3. A lock-out switching system for a two-way radio-telephone installation having a centrally located unit of transceiver apparatus and two control stations, each comprising a hand-set and associated hook-switch, a power supply switch and a push-button switch, each of said power supply switches, being normally effective independently of the setting ofthe other said power supply switch for switching a power supply for said apparatus on and oif, a relay operable by either of said push-buttonsfor transferring control of said transceiver apparatus to a control station which is to initiateor to receive a call, and a lock-out relay operable by closure of a circuit through the hook-switch of the last said control station, said lock-out relay constituting means for protecting that control'station against interruption of its service, listening in or otherwise interfering with a conversation by manipulation of either. the power supply switch, the push button or the hook switch at the other control station.

4. In a twoway radio-telephone system, transmitting and receiving apparatus housed as one unit, two separate control-units remotely situated from said' apparatus and from each other, each control unit comprising a'power supply switch, a push-button switch anda, telephone hook switch, a'single relay normally subject to energization by one of said push-button switches and normally subject to de-energization by the other of said push-button, switches, said relay being operable to provide exclusive control of said apparatus from the control unit whose. push-button is first depressed, asecondsinglarelay. operable by circuit closure through'the'telephone hook switch of the control unit which has assumed exclusive control, and circuits controlled by the last said relay for preventing the control of said apparatus by the control unit which has not assumed control.

5. The combination according to claim 4 wherein the circuits controlled by the last said relay include a power supply circuit which when closed by-passes said power supply switches.

6. The combination according to claim 4 wherein the circuits controlled by the last said relay inlclude means for rendering ineffective the operation of the push-button switch as the control unit which has not assumed control.

7. Switching equipment for locking out the use of a second telephone instrument and its associated control unit, during the holding of a con* versation from a rst telephone instrument, said equipment comprising two control units, one for each telephone instrument, each control unit comprising a three-way switch, an on-off switch and a switch hook, circuit means controlled by either one of said three-way switches for supplying power from a given source to a centrally located transceiver unit, self-locking relay means controlled by the ori-off switch at one of said control units and capable of being un locked by the opening of the on-off switch at the other of said control units, said relay means being operable to maintain exclusive control of said transceiver unit by a control unit which is selected for placing or receiving a call, and additional relay means subject to control by lifting a. telephone instrument from one of said switch hooks for locking out the use of the other control unit.

8. In combination, for use in a telephone station having two separate telephone hand-sets and associated control units each selectively connectable to a single two-way telephone apparatus unit, interconnecting three-way switches at the two control units operable to close or to open a power supply circuit for said apparatus unit, a normally open switch at one of said control units and a normally closed switch at the other of said control units, a first relay controllable on and off respectively by said normally open and normally closed switches, a telephone switch-hook associated with each said hand-set and operable thereby, and a second relay having its winding connectable across said power supply circuit through a selected one of said switch-hooks, said second relay constituting means whereby privacy of control and conversation is maintained by the control station and associated hand-set first to be used, the other said control station being prevented meanwhile irom breaking in or otherwise disturbing a telephone conversation held at said rst-to-be-used control station.

GEORGE G. BRADLEY. HARRY F. MOHR.

REFERENCES CITED The following references are of record in the ile of this patent:

UNITED STATES PATENTS Campbell Jan. 6, 1942 

